A backlight module is one of the crucial components of a liquid crystal display device. Because a liquid crystal display panel can not emit light, the function of the backlight module is to provide a light source of enough luminance and uniform distribution for the liquid crystal display device, so that the liquid crystal display device displays the image normally.
As shown in FIG. 1, in the current LED backlight, a PCB board 2 for installing a LED 3 is directly mounted on a backplane 5. The heat emitted by the LED 3 is dissipated into the air through the backplane 5; at the same time, because the backplane 5 directly contacts with some optical components, such as a light guide plate 4, etc, the quite number of heat is conducted to the inner of a backlight cavity. When the optical components are placed in a high-temperature field over a long period, the optical components will have many problems, such as aging, as well as stress, bending and accuracy control of tolerance caused by the thermal expansion and cold contraction, etc.